Static Acceleration

8.1 Static Vehicle

The vehicle at static situation is analyzed in this section. After simplifying the model, there is only three forces acting on the vehicle which are the total weight of car and driver, and the normal forces acting on the front and rear wheels.

The mass of vehicle and driver was estimated above as 303 kg, which gives the weight of:

[pic 1]

where the vehicle is supported by two normal forces, FN1 and FN2.

[pic 2]

Since the weight distribution of static vehicle was assumed as 40%/60% for front axel to rear axel, the normal forces can be calculated by:

[pic 3]

[pic 4]

There are two normal forces supporting the vehicle, and each of normal force is acting on two wheels thus, the normal force of each wheel can be calculated as:

[pic 5]

[pic 6]

8.2 Linear Acceleration

Variables:

• a: the average acceleration of vehicle

the rest is same as deceleration

When a vehicle is on the linear acceleration, the longitudinal load transfer takes place. The load shifts rearward when the vehicle is accelerating and frontward when it is decelerating. The maximum acceleration is estimated as 7.4 m/s2 (from 0 to 100 km/s in 3.75 s) then the longitudinal load transfer can be calculated by:

[pic 7]

The normal force acting on the front tire can be calculated as:

[pic 8]

The normal force acting on the rear tire can be calculated as:

[pic 9]

8.3 Deceleration

The braking system converts the kinetic energy of the car motion into heat energy. This is what allows the car to decelerate. In the event of braking, with the condition that the vehicle is moving in the same direction of the front tires, one of the major issues is the weight transfer from the rear tires to the front tires. It is necessary to calculate the weight transfer, based on an average coefficient of friction between the tires and the road, in order to understand the impact it will have on the front braking system and suspension